Catalytic monolith, method of its formulation and combustion process using the catalytic monolith

ABSTRACT

A catalyst system in which the catalytic composition comprises a catalytically active material which is homogeneously interspersed throughout a monolith structure of ceramic composition. The composition is shaped into a unitary monolith which is employed as the catalyst structure. In the method the active material or materials are admixed with a ceramic material, which can be either active or inactive, in finely divided form and then shaped into the monolith structure.

The invention described herein was made in the course of, or under, acontract with the Environmental Protection Agency.

This invention relates to catalyst systems, compositions and methods forthe formulation of such compositions. More particularly, the inventionrelates to catalyst systems in which the active material ishomogeneously interspersed throughout a monolith structure of ceramiccomposition.

Presently known catalyst systems for use in applications such ascombustors employ surface active materials in the form of pure pelletsof the active material, or in the form of a surface coating of theactive material on substrates such as ceramics. For example, it is wellknown to apply a catalyst material by slip coating onto a ceramicsubstrate which is in a honeycomb or other suitable monolith structure.For certain applications, such as gas turbine combustors, monolithicstructures are most advantageous.

The disadvantages and limitations of conventional monolithic catalystsystems include the problem of loss of the active material by flakingoff or volatilization from the substrate with a resulting loss incatalytic activity, or the problem of a change in the mechanicalproperties of the structures, due to an interaction of the catalystcoating and the monolith. In certain application, e.g. in combustors forgas turbines, the flaking material can cause erosion and damage toturbine blades, or the weakened catalyst/support can undergothermostructural failure and enter the turbine, causing damage to theblades.

It is an object of the present invention to provide new and improvedcatalyst systems and compositions and methods of formulating thecompositions.

Another object is to provide a catalyst system of the type described inwhich the active material is an integral part of the monolith structureto obviate the problems of coating flake-off or volatilization andconsequent loss of catalytic activity.

Another object is to provide a catalyst system in which the integrity ofthe monolith structure is maintained during sustained combustion whileobviating the problem of undesirable interaction of a catalyst metalwith a substrate which results in structural weakening.

Another object is to provide a catalyst system which provides relativelylonger operating life, especially in high temperature applications, andwhich provides good performance through relatively higher combustionefficiency over a long period of time.

Another object is to provide a catalyst system which achieves relativelygood catalytic activity wherein the light-off temperatures of thesystems compare favorably to the light-off temperatures of catalystsystems employing noble metals.

The invention in summary comprises a system in which the catalyticcomposition includes a catalytically active material which ishomogeneously interspersed throughout a monolith structure of ceramiccomposition. The composition is shaped into a unitary monolith which isemployed as the catalyst structure. In one version of the method theactive material or materials are admixed with a ceramic material, whichcan be either active or inactive, in finely divided form and then shapedinto the monolith structure which is calcined. The combustion process ofthe invention comprises combusting reactants in the presence of themonolithic catalytic structures.

The foregoing and additional objects and features of the invention willappear from the following specification in which the several embodimentsare set forth.

The catalyst systems of the invention are comprised in general of acatalytically active metal oxide material homogeneously mixed orinterspersed in a ceramic metal oxide material. The mixture can beshaped into a unitary monolith of the desired configuration. Theresulting monolith is thereby comprised throughout of the catalyticallyactive material to provide a catalysis system with a high degree ofstructural integrity and with improved performance.

In one embodiment of the invention the active material is a metal oxidewhich is homogeneously mixed throughout an inactive (or less active)metal oxide, which can be a mixed metal oxide.

Examples of the active metal oxides suitable for use in this embodimentinclude:

NiO

CeO₂

Fe₃ O₄

CrO₂

LaCrO₃

Co₂ O₃

CoAl₂ O₄

Examples of the inactive (or less active) materials suitable for use inthis embodiment include:

Zirconia Spinel

Yttria-stabilized zirconia

MgAl₂ O₄

SrZrO₃

CaZrO₃

Examples of the catalyst systems formed by the above materials for thisembodiment include:

Zirconia Spinel doped with nickel oxide (5% by weight)

Yttria-stabilized zirconia doped with nickel oxide (5% by weight)

Cerium Oxide (80% by weight) with zirconia (20% by weight)

Cerium Oxide (17% by weight) with zirconia (78% by weight) with nickeloxide dopant (5% by weight)

SrCrO₃ Perovskite doped with Co₂ O₃ (5% by weight)

CaZrO₃ doped with Co₂ O₃ (5% by weight)

CaZrO₃ arc-plasma sprayed with CoAl₂ O₄ doped with MgAl₂ O₄ (5% byweight)

SrZrO₃ arc-plasma sprayed with CoAl₂ O₄ doped with MgAl₂ O₄ (5% byweight)

LaCrO₃ (10% by weight) with ZrO₂ (90% by weight)

Mg₀.25 Ni₀.75 Cr₂ O₄

MgAl₂ O₄ :Fe₃ O₄

In other embodiments of the invention the monolithic catalyticcomposition is of the perovskite, spinel, corundum or ilmenite crystalstructure type in which primary catalytically active metal oxidematerials are in intimate admixture with carriers comprising inactive oractive metal oxide materials which are capable of forming ceramics. Theresulting composition comprises a random interspersion of the variouspossible crystal structures, e.g. of the perovskites, or the spinels, orthe corundum, or the ilmenite, as the case may be.

In one such embodiment a catalytically active base metal oxide of theperovskite crystal structure ABO₃ forms a solid solution with anothermaterial (either active or inactive) comprising a metal oxide of theperovskite structure ABO₃ suitable for formation of a ceramic. Generallythe perovskite structure is comprised of cations of different types ofmetals, one of type A and another of Type B and in which the cations areof different size with the smaller cations in the ccp (cubic closepacking) array occupying the octahedral holes formed exclusively by theoxide ions.

The following are examples of the primary active perovskite base metaloxides which can be employed in this embodiment:

LaCrO₃

LaNiO₃

LaMnO₃

La₀.5 Sr₀.5 MnO₃

La₀.8 K₀.2 Rh₀.1 Mn₀.9 O₃

ZrXWO₃ (X=Ni, Co)

LaCoFeO₃

LaMNiO₃ (M=Ca, or Sr)

The following are examples of perovskite type metal oxides suitable foruse as carrier materials in this embodiment:

LaAlO₃

(Sr₀.4 La₀.6)(Co₀.5 V₀.2)O₃

(Sr₀.2 La₀.8)CoO₃

(Sr₀.4 La₀.6)(Co₀.9 Pt₀.1)O₃

The following are examples of catalytically active perovskite metaloxides in solid solution with perovskite metal oxides as carriers:

LaAlO₃ :LaCrO₃ (3:1 mole ratio)

LaAlO₃ :LaNiO₃ (3:1 mole ratio)

Another embodiment of the invention provides a primary catalyticallyactive metal oxide of the spinel crystal structure in solid solutionwith a spinel structured compound which is suitable for formation of aceramic. The spinel crystal structure takes the form A[B₂ ]O₄ or theinverse structure B[AB]O₄.

The following are examples of the primary active spinel metal oxideswhich can be employed in this embodiment:

Fe₃ O₄ (Fe occupies both the A and B sites of the spinel A[B₂ ]O₄crystal structure)

NiAl₂ O₄

Ni₀.5 MgO₀.5 (Al₀.5 Cr₀.3 Fe₀.2)₂ O₄

Ni(Al₀.3 Cr₀.5 Fe₀.2)₂ O₄ +NiO (1% by weight)

Co(Al₀.3 Cr₀.5 Fe₀.2)₂ O₄ +CoO (5% by weight)

MgCr₂ O₄

The following is an example of a spinel type metal oxide suitable foruse as the carrier material in this embodiment:

MgAl₂ O₄

The following are examples of the solid solutions of the catalyticallyactive spinel materials with the carrier spinel materials:

MgAl₂ O₄ :NiAl₂ O₄ (3:1 mole ratio)

MgAl₂ O₄ :MgCr₂ O₄ (3:1 mole ratio)

MgAl₂ O₄ :Fe₃ O₄ (9:1 mole ratio)

Alternatively, an oxide cermet such as the following spinel cermetexample can be used:

MgAl₂ O₄ :Fe₃ O₄ :(3:1 mole ratio)+40% Cr by weight

In another embodiment of the invention a primary catalytically activebase metal oxide of either the corundum B₂ O₃ or ilmenite ABO₃ crystalstructures forms a solid solution with another material (either activeor inactive) comprising a metal oxide of the corundum crystal structuresuitable for formation of a ceramic.

Examples of the primary active corundum oxides include:

Fe₂ O₃

Co₂ O₃ stabilized with Yttria

Examples of the primary active ilmenite oxides employed in thisembodiment include:

Cr₂ O₃ (Cr occupies both the A and B sites in the ilmenite ABO₃ crystalstructure)

Fe_(x) Mg_(1-x) TiO₃ (x between 0.85 and 0.90, for example)

An example of a corundum structured compound suitable for use in thisembodiment as the ceramic carrier comprises alumina.

Examples of solid solutions formed between ilmenite structured activecompounds and the corundum structured carrier comprise Cr₂ O₃ :Al₂ O₃(1:5 mole ratio) and Fe₀.85 Mg₀.15 TiO₃ :Al₂ O₃ (1:9 mole ratio)respectively.

Examples of solid solutions between active compounds and carriers whichare both of corundum structure include:

Al₂ O₃ :Fe₂ O₃ (3:1 mole ratio)

Al₂ O₃ :Co₂ O₃ (5:1 mole ratio) stabilized with Yttria (2% by weight)

From the potentially large number of metal oxide compounds which couldformulate into solid solutions of the foregoing type, it will berealized that those compounds containing metals with volatile oxides aregenerally unsuitable for combustor service. Thus, the many compoundscontaining barium, lead, rhenium, ruthenium, sodium and other volatilemetals are not preferred. Similarly, compounds containing halogens arenot considered useful for combustor service and are not preferred inthis invention. Additionally, compounds of the type with known meltingpoints below about 1873 K are suitable only for lower temperatureapplications.

One method of formulating the catalyst systems of the inventioncomprises selection of the starting material in a predeterminedproportion according to the mole weight formula of the compositiondesired for the resulting monolith structure. The starting compounds arepulverized and intermixed, such as by a ball mill or other method, toinsure complete dispersion and a small particle size on the order of 10to 20 microns. The mixture of powder is then formed into the shape whichis desired for the particular ceramic technique which is to be used toform the catalyst structure. The mixture is then fired at a temperatureof at least 1000° C.

As one example of a method of molding the catalyst structure to adesired shape, e.g. a honeycomb shape, would be to form an aqueous ororganic slurry with the reactive powders and a binder, pour the slurryinto a mold, apply heat to drive off the water and binder, and thensinter at the high temperature. Another example would be to apply acoating of such a mixture to a substrate such as paper formed into thedesired shape and then burn the paper off. Another example for use whereone of the starting materials is a pure compound such as alumina wouldbe to press the powders together into the desired shape and then causethem to react.

The following is a specific example of a method of formulating aperovskite-based catalyst system which is a solid solution of LaAlO₃ andLaCrO₃. Ammonium dichromate (NH₄)₂ Cr₂ O₃ is dissolved in deionizedwater. Added to that solution is the appropriate mole percentage of La₂O₃. Added to that mixture is a reactive alumina in the appropriate molepercentage. The resulting mixture is dried at about 150° C. to form asludge, then calcined at a temperature above about 600° C. The resultingpowder is ball milled and then recalcined above 1300° C. A sample of therecalcined material may be checked by X-ray diffraction. If reaction isnot complete, the powder is recalcined until the desired state isachieved.

At this stage the powder which has been made is a completely reactedcomposition of the base metal oxide. The reacted powder is ball milledwith water or other suitable liquid to develope a rheology suited to thechosen forming method, then formed and shaped into the desired unitaryconfiguration.

Another method for making materials suitable for this invention is bygelling solutions of the proper composition of the desired metals. Inthis case the gel may be spray-dried to provide a powder of the properrheology for further processing.

After the powder has been brought to the proper rheology, the shapingstep may be carried out by formation of a water-based slip (withappropriate organic binders and dispersants) and then casting,extruding, molding or pressing the material into the desired shape. Thisstep may comprise coating of the slip onto a paper, polymer or spongesubstrate, after which the substrate can be removed as by firing.

The final step in this method is calcining the resultant monolithmaterial in the range of 1100°-1600° C. It is preferable to calcine inan oxidizing atmosphere. However, with constituents having oxides suchas Cr₂ O₃, which have some volatility, it may be necessary to calcineunder an inert atmosphere such as argon. If the material is calcinedunder a forming gas to reduce the chance of oxide vaporization, a sampleof it must be checked by X-ray diffraction to make sure that segregatedreduced phases have not been introduced.

The following is a specific example of a method of forming a catalystsystem with a corundum-based active ceramic. In the first stepappropriate mole percentages of (NH₄)₂ Cr₂ O₇ and Al₂ O₃ (reactive) areadded to deionized water using suitable dispersants. The slurry is driedat 150° C. to a sludge, the sludge is calcined at a temperature of 600°C. and the resulting powder is ball milled. The remaining steps arecarried out as set forth in the above example for the perovskite-basedsystem.

The following is a specific example of a method of forming aspinel-based metal oxide catalyst system which is a solid solution ofMgAl₂ O₄ and NiAl₂ O₄. Basic magnesium carbonate MgCO₃.Mg(OH)₂. 3H₂ O isdispersed in deionized water, and to that mixture are added suitablequantities of reactive Al₂ O₃ and Ni(CO₃). The product is then dried at150° C. to a sludge, and the sludge is calcined at a temperature rangeof 1000° C.-1300° C. The remaining steps are carried out as in theabove-described example for the method of preparing the perovskite-basedsystem.

The following is a specific example of a method of formulating anotherspinel-based system which is a solid solution of MgAl₂ O₄ and MgCr₂ O₄.In the first step (NH₄)₂ Cr₂ O₇ is dispersed in deionized water. To thatmixture appropriate quantities of basic magnesium carbonate and reactiveAl₂ O₃ are added as well as a dispersant. The remaining steps arecarried out as described in the immediately preceding example.

In the method of forming catalyst systems based upon the above-describedgeneral ceramic materials, a common catalytic substrate having severalpercent (preferably from 1 to 10% but up to 25%) of a catalyticallyactive metal oxide is added to the material before monolith formation.For example, nickel oxide in yttria-stabilized zirconia; nickel oxide orchromium oxide in mullite or cordierite or zircon mullite; LaCrO₃ andmullite; MgCr₂ O₄ and alumina; or nickel oxide or Co₂ O₃ and alumina.The material is then shaped as described above in connection with theperovskite-based system. Longer times at calcining temperatures may berequired to insure that any solid state reaction is complete duringformulation.

Another preferred embodiment of the present invention is the use ofcatalytically-active oxide composition as both the catalytic and thestructural materials. Although there are many advantages to be gained bymixing active materials with less-active materials, it is oftendesirable to use the active oxide composition for the catalytic andstructural materials. An example of this is the use of LaCrO₃ as theperforming catalytically active, electrically-conducting monolithmaterial.

EXAMPLE I

Oxide powders of MgAl₂ O₄ and NiAl₂ O₄ (3:1 mole ratio) were prepared bypressing the powders into discs and calcining in the manner describedabove. The disc size was 21/4" in diameter and 11/4" long with 18 to 30holes of 0.25" diameter drilled axially to form gas flow passages. Theresulting monolith structure was tested in a combustor using air andnatural gas reactants under fuel-lean conditions down to a minimumpreheat of 325° F. Blowout of the catalyst bed did not occur at thehighest throughput attained, 849,000 hr⁻¹ space velocity. The catalystwas also tested on lean diesel fuel and sustained combustion to aminimum preheat of 590° F. During the diesel fuel test blowout did notoccur during maximum throughput at a space velocity of 1,152,000 hr⁻¹.

The results of the test of the first example are listed in Table I. COemissions were below 50 ppm, and NO emissions ranged from 1 to 30 ppm.

EXAMPLE II

Powders of LaAlO₃ and LaCrO₃ (3:1 mole ratio) were pressed and calcinedinto discs shaped as described for Example I. The catalyst was tested ina combustor using reactants of air and natural gas as well as dieselfuel. The test results are depicted in Table II.

EXAMPLE III

Powders of MgAl₂ O₄ and Fe₃ O₄ (3:1 mole ratio) were pressed andcalcined into pellets shaped as described in Example I. The catalyst wastested in a combustor on lean natural gas and lean diesel fuel. The testresults are set forth in Table III.

EXAMPLE IV

Powders of MgAl₂ O₄ and MgCr₂ O₄ (3:1 mole ratio) were pressed andcalcined into the shape of tubes 2" in length having nominal dimensionsof 1/4" OD and 1/8" ID. Forty-four of these tubes were bundled andwrapped together in insulation and supported vertically within a holdertube on a disc of Torvex alumina 1" long by 2" diameter which washoneycombed with 3/16" diameter cells. The catalyst structure was testedon air and lean and rich natural gas and diesel fuel. The results of thetest are depicted in Table IV. The performance shows that on leannatural gas CO and NO emissions were at or below 18 and 10 ppmrespectively. There was no loss in catalytic activity after 5 hours oftesting.

EXAMPLE V

Powders of Al₂ O₃ and Cr₂ O₃ (9:1 mole ratio) were pressed and calcinedinto the shape of tubes 2" in length having nominal dimensions of 1/4"OD and 1/8" ID. A plurality of the tubes were bundled, wrapped togetherand supported in the manner described above for example IV. Platinum wasadded to the front segment to promote light-off. The catalyst structurewas tested on air and natural gas. The results of the test are depictedin Table V.

From the foregoing it will be seen that the catalyst system compositionsof the present invention provide good performance with high combustionefficiency over a long period of time. The catalytic monolith maintainsits structural integrity in operation without loss of catalytic activitythrough flake-off or volatilization. There is no problem of interactionof base metal catalysts with the substrate, nor is there the problem ofdegradation of surface area due to growth in crystallite size of theactive component when in operation so that there is a relatively longerlife, especially in high temperature applications. Additionally, themanufacturing process is relatively less expensive in that there arefewer steps to formulate the monolith structure as compared to existingtechniques of manufacturing a substrate, applying a wash coat and thenapplying the catalyst.

While the foregoing embodiments are at present considered to bepreferred, it is understood that numerous variations and modificationsmay be made therein by those skilled in the art and it is intended tocover in the appended claims all such variations and modifications asfall within the true spirit and scope of the invention.

                                      TABLE I                                     __________________________________________________________________________    Test                                                                              TA SV   .m.sub.fuel                                                                        .m.sub.air                                                                          T.sub.ph                                                                         T.sub.bed                                                                       Velocity                                                                           CO  NO  UHC Q                                point                                                                             (%)                                                                              (l/hr)                                                                             (lbm/hr)                                                                           (lbm/hr)                                                                           (°F.)                                                                     (°F.)                                                                     (ft/sec)                                                                           (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (Btu/hr)                                                                           Test type                   __________________________________________________________________________    41-6                                                                              191                                                                              387,000                                                                            2.36 77.4 668                                                                              2000                                                                             9.0  10  4   0   50,700                                                                             Stabilizing                 41-7                                                                              "  "    "    "    618                                                                              2025                                                                             "    "   "   "   "    on natural                  41-8                                                                              "  "    "    "    613                                                                              2020                                                                             "    "   "   "   "    gas                         41-9                                                                              "  "    "    "    610                                                                              2020                                                                             "    "   "   "   "    "                           41-10                                                                             "  "    "    "    610                                                                              2020                                                                             "    13  "   1   "    "                           41-11                                                                             "  "    "    "    609                                                                              2010                                                                             "    10  "   0   "    "                           41-12                                                                             "  "    "    "    610                                                                              "  "    "   "   "   "    "                           41-13                                                                             "  "    "    "    608                                                                              "  "    "   "   "   "    "                           41-14                                                                             "  "    "    "    607                                                                              "  "    "   5   "   "    "                           41-15                                                                             "  "    "    "    607                                                                              2005                                                                             "    8   "   "   "    "                           41-16                                                                             "  "    "    "    609                                                                              2005                                                                             "    "   "   "   "    "                           41-17                                                                             188                                                                              381,000                                                                            2.36 77.4 575                                                                              2010                                                                             8.6  6   5   0   50,700                                                                             Minimum pre-                41-18                                                                             186                                                                              376,000                                                                            "    75.2 550                                                                              2010                                                                             8.7  8   "   "   "    heat, lean,                 41-19                                                                             183                                                                              372,000                                                                            "    74.2 500                                                                              2010                                                                             8.6  8   "   "   "    on natural                  41-20                                                                             181                                                                              367,000                                                                            "    73.3 475                                                                              2005                                                                             8.5  10  "   "   "    gas                         41- 21                                                                            174                                                                              353,000                                                                            "    70.4 450                                                                              "  8.2  "   6   "   "    "                           41-22                                                                             172                                                                              349,000                                                                            "    69.4 425                                                                              "  8.1  "   "   "   "    "                           41-23                                                                             169                                                                              344,000                                                                            "    68.4 400                                                                              "  8.0  9   "   "   "    "                           41-24                                                                             162                                                                              330,000                                                                            "    65.5 375                                                                              2015                                                                             7.7  10  7   "   "    "                           41-25                                                                             160                                                                              326,000                                                                            "    64.5 350                                                                              2005                                                                             7.5  "   8   "   "    "                           41-26                                                                             157                                                                              321,000                                                                            "    63.6 325                                                                              2005                                                                             7.4  "   8   "   "    "                           41-27                                                                             152                                                                              312,000                                                                            "    61.6 335                                                                              2015                                                                             7.2  "   9   "   "    "                           41-34                                                                              52                                                                              219,000                                                                            4.29 38.4 523                                                                              1960                                                                             5.1  --  2   6800                                                                              92,200                                                                             Rich conditions             41-37                                                                              52                                                                              219,000                                                                            4.29 38.4 658                                                                              2030                                                                             5.1  --  1   3100                                                                              92,200                                                                             on natural gas,                                                               unstable                    41-40                                                                             198                                                                              399,000                                                                            2.36 80.0 801                                                                              2015                                                                             9.2  --  5   0   50,700                                                                             Maximum                     41-41                                                                             204                                                                              495,000                                                                            2.84 99.4 793                                                                              2060                                                                             11.5 --  4   "   61,100                                                                             throughput,                 41-42                                                                             193                                                                              545,000                                                                            3.30 109. 790                                                                              2070                                                                             12.6 43  5   "   71,000                                                                             natural gas,                41-43                                                                             212                                                                              687,000                                                                            3.81 138. 793                                                                              2085                                                                             15.9 43  3   "   82,000                                                                             lean                        41-44                                                                             249                                                                              849,000                                                                            4.02 172. 789                                                                              2025                                                                             19.7 40  2   "   86,400                                                                             "                           41-47                                                                             173                                                                              365,000                                                                            2.89 77.1 708                                                                              2090                                                                             8.5  0   16  0   62,100                                                                             Minimum pre-                41-48                                                                             "  "    "    "    692                                                                              2115                                                                             "    45  "   "   "    heat, lean,                 41-49                                                                             "  "    "    "    663                                                                              2115                                                                             "    43  "   "   "    condensed fuel              41-50                                                                             "  "    "    "    642                                                                              2110                                                                             "    38  "   "   "    "                           41-51                                                                             "  "    "    "    626                                                                              2100                                                                             "    45  15  "   "    "                           41-52                                                                             170                                                                              356,000                                                                            "    75.2 603                                                                              2075                                                                             8.2  48  16  "   "    "                           41-53                                                                             170                                                                              356,000                                                                            "    75.2 596                                                                              2025                                                                             8.2  25  17  "   "    "                           41-58                                                                             164                                                                              356,000                                                                            2.97 75.2 876                                                                              2140                                                                             8.2  44  30  0.5 54,100                                                                             Maximum                     41-59                                                                             171                                                                              425,000                                                                            3.41 89.7 863                                                                              2200                                                                             9.8  --  --  --  62,200                                                                             throughput                  41-60                                                                             181                                                                              562,000                                                                            4.26 119. 860                                                                              2100                                                                             13.0 40  25  0.5 77,700                                                                             diesel fuel,                41-61                                                                             188                                                                              677,000                                                                            4.92 143. 872                                                                              2260                                                                             15.7 40  23  "   89,700                                                                             lean                        41-62                                                                             178                                                                              723,000                                                                            5.58 153. 878                                                                              2325                                                                             16.7 --  33  "   101,700                                                                            "                           41-63                                                                             194                                                                              883,000                                                                            6.23 186. 895                                                                              2350                                                                             20.5 13  24  "   113,600                                                                            "                           41-64                                                                             200                                                                              1,152,000                                                                          7.87 243. 867                                                                              2240                                                                             26.7 15  18  "   143,500                                                                            "                           41-65                                                                             185                                                                              1,152,000                                                                          8.53 243. 860                                                                              2340                                                                             26.7 30  21  "   155,500                                                                            "                           __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    Test                                                                              TA SV   .m.sub.fuel                                                                        .m.sub.air                                                                          T.sub.ph                                                                         T.sub.bed                                                                       Velocity                                                                           NO  UHC Q                                    point                                                                             (%)                                                                              (l/hr)                                                                             (lbm/hr)                                                                           (lbm/hr)                                                                           (°F.)                                                                     (°F.)                                                                     (ft/sec)                                                                           (ppm)                                                                             (ppm)                                                                             (Btu/hr)                                                                           Test type                       __________________________________________________________________________    42-4                                                                              191                                                                              460,000                                                                            2.36 77.4 630                                                                              2120                                                                             10.6 3   0   50,700                                                                             Stabilizing on                  42-5                                                                              "  "    "    "    630                                                                              2110                                                                             "    4   1   "    natural gas                     42-6                                                                              "  "    "    "    630                                                                              "  "    4   "   "    "                               42-7                                                                              "  "    "    "    631                                                                              "  "    4   "   "    "                               42-8                                                                              "  "    "    "    631                                                                              "  "    5   "   "    "                               42-9                                                                              "  "    "    "    632                                                                              "  "    5   "   "    "                               42-10                                                                             "  "    "    "    634                                                                              2120                                                                             "    6   "   "    "                               42-11                                                                             191                                                                              460,000                                                                            2.36 77.4 570                                                                              2110                                                                             10.6 6   1   50,700                                                                             Minimum preheat                 42-12                                                                             183                                                                              442,000                                                                            "    75.2 548                                                                              2110                                                                             10.2 "   "   "    lean, natural                   42-13                                                                             181                                                                              437,000                                                                            "    73.3 525                                                                              2100                                                                             10.1 "   "   "    gas                             42-14                                                                             174                                                                              421,000                                                                            "    70.4 500                                                                              2100                                                                             9.7  "   "   "    "                               42-15                                                                             169                                                                              410,000                                                                            "    68.4 450                                                                              2090                                                                             9.4  7   "   "    "                               42-16                                                                             162                                                                              393,000                                                                            "    65.5 425                                                                              2100                                                                             9.1  8   "   "    "                               42-17                                                                             157                                                                              382,000                                                                            "    63.6 400                                                                              2110                                                                             8.9  9   "   "    "                               42-18                                                                             157                                                                              382,000                                                                            "    63.6 377                                                                              2100                                                                             8.9  8   "   "    "                               42-19                                                                              52                                                                              260,000                                                                            4.29 38.4 500                                                                              2120                                                                             6.0  4   5300                                                                              92,200                                                                             Minimum preheat,                42-20                                                                              56                                                                              277,000                                                                            "    41.3 474                                                                              2110                                                                             6.4  3   2500                                                                              "    rich, natural                   42-21                                                                              56                                                                              277,000                                                                            "    41.3 450                                                                              2100                                                                             6.4  3   3000                                                                              "    gas                             42-22                                                                              60                                                                              293,000                                                                            "    44.2 390                                                                              1970                                                                             6.8  6    900                                                                              "    "                               42-23                                                                              63                                                                              284,000                                                                            "    46.2 375                                                                              2025                                                                             7.0  16   400                                                                              "    "                               42-25                                                                             206                                                                              589,000                                                                            1.05 99.4 690                                                                              2125                                                                             13.6 7   1   60,600                                                                             Maximum                         42-26                                                                             210                                                                              703,000                                                                            1.23 119. 689                                                                              2100                                                                             16.3 7   "   71,000                                                                             throughput,                     42-27                                                                             207                                                                              789,000                                                                            1.40 133. 689                                                                              2160                                                                             18.3 7   "   80,600                                                                             natural gas,                    42-28                                                                             214                                                                              874,000                                                                            1.50 148. 691                                                                              2160                                                                             20.2 6   "   86,400                                                                             lean                            42-29                                                                             184                                                                              425,000                                                                            2.66 75.5 790                                                                              2140                                                                             9.8  --  --  48,500                                                                             Minimum preheat,                42-30                                                                             "  "    "    "    766                                                                              2140                                                                             "    11  4   "    lean, diesel fuel               42-31                                                                             "  "    "    "    725                                                                              2160                                                                             "    12  3   "    "                               42-32                                                                             "  "    "    "    700                                                                              2160                                                                             "    13  "   "    "                               42-33                                                                             182                                                                              420,000                                                                            "    74.5 650                                                                              2140                                                                             9.7  12  "   "    "                               42-34                                                                             172                                                                              398,000                                                                            "    70.6 623                                                                              2150                                                                             9.2  15  "   "    "                               42-35                                                                             161                                                                              371,000                                                                            "    65.8 600                                                                              1770                                                                             8.6  20  2   "    "                               42-37                                                                             196                                                                              753,000                                                                            4.43 133.5                                                                              750                                                                              2240                                                                             17.4 12  18  80,800                                                                             Maximum through-                42-38                                                                             189                                                                              944,000                                                                            5.74 167. 772                                                                              2140                                                                             21.8 18  17  10,500                                                                             put, diesel fuel,               42-39                                                                             191                                                                              1,124,000                                                                          6.76 199. 792                                                                              1650                                                                             26.0 16  15  123,000                                                                            lean                            __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________    Test                                                                              TA SV    .m.sub.fuel                                                                       .m.sub.air                                                                         T.sub.ph                                                                         T.sub.bed                                                                        Velocity                                                                           CO  NO  UHC Q                                point                                                                             (%)                                                                              (l/hr)                                                                             (lbm/hr)                                                                           (lbm/hr)                                                                           (°F.)                                                                     (°F.)                                                                     (ft/sec)                                                                           (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (Btu/hr)                                                                           Test Type                   __________________________________________________________________________    45-2                                                                              191                                                                              395,000                                                                            2.36 77.4 730                                                                              2260                                                                             11.4 --  4   0   50,700                                                                             Stabilizing on              45-3                                                                              "  "    "    "    "  "  "    --  5   3   "    natural gas                 45-4                                                                              "  "    "    "    "  "  "    --  5   0   "    "                           45-5                                                                              "  "    "    "    "  "  "    --  5   "   "    "                           45-6                                                                              "  "    "    "    "  "  "    --  4   "   "    "                           45-7                                                                              "  "    "    "    "  "  "    --  5   "   "    "                           45-11                                                                             191                                                                              395,000                                                                            2.36 77.4 778                                                                              2280                                                                             11.4 25  6   0   50,700                                                                             Minimum pre-                45-12                                                                             "  "    "    "    774                                                                              2280                                                                             "    20  5   "   "    heat, lean,                 45-13                                                                             "  "    "    "    700                                                                              2250                                                                             "    20  4   "   "    natural gas                 45-14                                                                             "  "    "    "    675                                                                              2240                                                                             "    25   4  "   "    "                           45-15                                                                             179                                                                              371,000                                                                            "    72.6 625                                                                              2250                                                                             10.8  0  6   2   "    "                           45-16                                                                             179                                                                              371,000                                                                            "    72.6 600                                                                              "  10.8 "   5   "   "    "                           45-17                                                                             175                                                                              362,000                                                                            "    70.6 575                                                                              "  10.5 "   6   "   "    "                           45-18                                                                             172                                                                              357,000                                                                            "    69.7 550                                                                              "  10.3 "   "   "   "    "                           45-19                                                                             170                                                                              353,000                                                                            "    68.7 525                                                                              2240                                                                             10.2 "   "   "   "    "                           45-20                                                                             167                                                                              348,000                                                                            "    67.7 500                                                                              2240                                                                             10.1 "   "   "   "    "                           45-26                                                                             191                                                                              395,000                                                                            2.36 77.4 860                                                                              2200                                                                             11.4  0  7   0   50,700                                                                             Maximum                     45-27                                                                             211                                                                              604,000                                                                            3.30 119. 824                                                                              2240                                                                             17.5 "   5   "   71,000                                                                             throughput,                 45-28                                                                             214                                                                              702,000                                                                            3.78 138. 817                                                                              2250                                                                             20.3 "   4   "   81,300                                                                             natural gas                 45-29                                                                             213                                                                              751,000                                                                            4.05 148  806                                                                              2250                                                                             21.8 "   4   "   87,100                                                                             "                           45-30                                                                             187                                                                              388,000                                                                            2.79 80.3 794                                                                              2310                                                                             11.2 --  15  0   50,900                                                                             Minimum pre-                45-31                                                                             182                                                                              379,000                                                                            "    78.4 750                                                                              2300                                                                             11.0 --  14  "   "    heat, lean,                 45-32                                                                             182                                                                              379,000                                                                            "    78.4 700                                                                              2320                                                                             11.0 --  15  "   "    diesel                      45-33                                                                             182                                                                              379,000                                                                            "    78.4 650                                                                              2300                                                                             11.0 --  "   "   "    "                           45-34                                                                             180                                                                              374,000                                                                            "    77.4 625                                                                              "  10.8 --  "   "   "    "                           45-35                                                                             176                                                                              365,000                                                                            "    75.5 600                                                                              "  10.6 --  "   "   "    "                           45-36                                                                             171                                                                              355,000                                                                            "    73.5 575                                                                              "  10.3 --  17  "   "    "                           45-37                                                                             167                                                                              346,000                                                                            "    71.6 550                                                                              "  10.0 --  17  "   "    "                           45-38                                                                             162                                                                              337,000                                                                            "    69.7 525                                                                              "  9.8  --  18  "   "    "                           45-39                                                                             158                                                                              327,000                                                                            "    67.7 490                                                                              2320                                                                             9.5  --  21  "   "    "                           45-40                                                                             153                                                                              318,000                                                                            "    65.8 475                                                                              2350                                                                             9.2  --  23  "   "    "                           45-41                                                                             153                                                                              318,000                                                                            "    65.8 450                                                                              2300                                                                             9.2  --  22  "   "    "                           45-42                                                                             149                                                                              309,000                                                                            "    63.9 425                                                                              2340                                                                             8.9  --  23  "   "    "                           45-43                                                                             144                                                                              299,000                                                                            "    61.9 395                                                                              2340                                                                             8.7  --  28  "   "    "                           45-44                                                                             142                                                                              295,000                                                                            "    61.0 375                                                                              2340                                                                             8.5  --  28  "   "    "                           45-45                                                                             142                                                                              295,000                                                                            "    61.0 348                                                                              2340                                                                             8.5  --  28  "   "    "                           45-46                                                                             140                                                                              290,000                                                                            "    60.0 325                                                                              2300                                                                             8.4  --  26  "   "    "                           45-47                                                                             137                                                                              285,000                                                                            "    59.0 300                                                                              2270                                                                             8.3  --  23  "   "    "                           45-48                                                                             122                                                                              253,000                                                                            "    52.3 275                                                                              2250                                                                             7.3  --  26  "   "    "                           45-49                                                                             117                                                                              243,000                                                                            "    50.3 255                                                                              2150                                                                             7.0  --  20  "   "    "                           45-52                                                                             182                                                                              374,000                                                                            2.89 77.4 794                                                                              2280                                                                             10.8 --  11  2   527,000                                                                            Maximum                     45-53                                                                             203                                                                              669,000                                                                            4.42 138. 781                                                                              2350                                                                             19.4 --  8   3   806,000                                                                            throughput,                 45-54                                                                             194                                                                              814,000                                                                            5.64 168. 794                                                                              2300                                                                             23.6 --  15  2   103,000                                                                            diesel fuel                 45-55                                                                             174                                                                              879,000                                                                            6.79 182. 793                                                                              2000                                                                             25.5 --  30  --  124,000                                                                            "                           45-56                                                                             140                                                                              290,000                                                                            2.79 60.0 351                                                                              2170                                                                             8.4  --  28  3   50,900                                                                             Minimum pre-                45-57                                                                             119                                                                              435,000                                                                            4.92 90.0 321                                                                              2250                                                                             12.6 --  --  --  89,700                                                                             heat, lean,                 45-58                                                                             119                                                                              435,000                                                                            4.92 90.0 304                                                                              2220                                                                             12.6 --  --  --  89,700                                                                             diesel at                                                                     higher through-                                                               put                         __________________________________________________________________________

                                      TABLE IV                                    __________________________________________________________________________    Test                                                                              TA SV    .m.sub.fuel                                                                        . m.sub.air                                                                         T.sub.ph                                                                         T.sub.bed                                                                        Velocity                                                                            CO  NO  HC  Q                             point                                                                             (%)                                                                              (l/hr)                                                                              (lbm/hr)                                                                           (lbm/hr)                                                                            (°F.)                                                                     (°F.)                                                                     (ft/sec)                                                                            (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (Btu/hr)                                                                           Test                     __________________________________________________________________________                                                         type                     46-2                                                                              222                                                                              321,000                                                                             2.36 90.0  724                                                                              2450                                                                             14.9   8  4   0   50,700                                                                             Minimum preheat          46-3                                                                              222                                                                              321,000                                                                             "    90.0  699                                                                              2450                                                                             14.9  10  5   "   "    lean, natural            46-4                                                                              218                                                                              315,000                                                                             "    88.1  640                                                                              2450                                                                             14.6  10  7   "   "    gas                      46-5                                                                              203                                                                              295,000                                                                             "    82.3  611                                                                              2400                                                                             13.7  13  "   "   "    "                        46-6                                                                              199                                                                              288,000                                                                             "    80.3  575                                                                              2425                                                                             13.4  13  "   "   "    "                        46-7                                                                              196                                                                              285,000                                                                             "    79.4  550                                                                              2350                                                                             13.2  15  "   "   "    "                        46-8                                                                              191                                                                              279,000                                                                             "    77.4  525                                                                              -- 12.9  --  --  "   "    "                        46-9                                                                              187                                                                              272,000                                                                             "    75.5  500                                                                              2480                                                                             12.6  15  8   "   "    "                        46-10                                                                             182                                                                              265,000                                                                             "    73.5  475                                                                              2550                                                                             12.3  "   "   "   "    "                        46-11                                                                             "  "     "    "     450                                                                              2620                                                                             "     "   "   "   "    "                        46-12                                                                             "  "     "    "     425                                                                              2600                                                                             "     "   "   "   "    "                        46-13                                                                             "  "     "    "     400                                                                              2550                                                                             "     13  "   "   "    "                        46-14                                                                             179                                                                              262,000                                                                             "    72.6  375                                                                              2500                                                                             12.1  --  "   "   "    "                        46-15                                                                             179                                                                              262,000                                                                             "    72.6  350                                                                              2550                                                                             12.1  15  "   "   "    "                        46-16                                                                             179                                                                              262,000                                                                             "    72.6  325                                                                              2525                                                                             12.1  10  "   "   "    "                        46-17                                                                             175                                                                              255,000                                                                             "    70.6  300                                                                              2525                                                                             11.8  15  "   "   "    "                        46-18                                                                             175                                                                              255,000                                                                             "    70.6  275                                                                              2500                                                                             11.8  "   "   "   "    "                        46-19                                                                             175                                                                              255,000                                                                             "    70.6  250                                                                              2500                                                                             11.8  "   "   "   "    "                        46-20                                                                             170                                                                              249,000                                                                             "    68.7  178*                                                                             2450                                                                             11.5  "   "   "   "    "                        46-23                                                                              50                                                                              152,000                                                                             4.29 36.8  674                                                                              2620                                                                              7.0  --  6   6000                                                                              92,000                                                                             Unstable on nat-                                                              ural gas, rich           46-25                                                                             234                                                                              338,000                                                                             2.36 94.8  824                                                                              2450                                                                             15.7  18  10  0   50,700                                                                             Maximum through-         46-26                                                                             227                                                                              390,000                                                                             2.82 109.  780                                                                              2450                                                                             18.1  15  8   "   60,600                                                                             put, lean, nat-          46-27                                                                             212                                                                              426,000                                                                             3.27 119.  780                                                                              2480                                                                             19.7  13  "   "   70,300                                                                             ural gas                 46-28                                                                             208                                                                              479,000                                                                             3.75 134.  789                                                                              2525                                                                             22.2  15  "   "   80,600                                                                             "                        46-29                                                                             213                                                                              530,000                                                                             4.05 148.  788                                                                              2500                                                                             24.5  10  "   "   87,100                                                                             "                        46-32                                                                             207                                                                              307,000                                                                             2.82 90.0  780                                                                              2550                                                                             14.2  20  7   0   60,600                                                                             Unstable on              46-33                                                                             207                                                                              307,000                                                                             2.82 90.0  804                                                                              2500                                                                             14.2  10  8   1   60,600                                                                             diesel fuel              46-35                                                                             175                                                                              472,000                                                                             5.12 138.  850                                                                              -- 21.9  10  9   10  112,600                                                                            "                        46-37                                                                             191                                                                              279,000                                                                             2.36 77.4  525                                                                              2450                                                                             12.9   5  5   0   50,700                                                                             Still catalyti-          46-38                                                                             191                                                                              279,000                                                                             2.36 77.4  497                                                                              2450                                                                             12.9   5  5   --  50,700                                                                             cally active on                                                               natural                  __________________________________________________________________________                                                         gas                       *Ambient                                                                 

                                      TABLE V                                     __________________________________________________________________________    Test                                                                              TA SV    .m.sub.CH.sbsb. 4                                                                  .m.sub.m air                                                                       T.sub.ph                                                                         T.sub.bed (°F.)                                                              CO  NO  HC                                    Point                                                                             (%)                                                                              (l/hr)                                                                              (lbm/hr)                                                                           (lbm/hr)                                                                           (°F.)                                                                     TR1                                                                              TR2                                                                              (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             Test Type                         __________________________________________________________________________    32-10                                                                             180                                                                              116,000                                                                             2.44 75.7 683                                                                              2520                                                                              800                                                                             20  30  8   Aging (bed nonuniform)            32-12                                                                             197                                                                              116,000                                                                             2.23 "    685                                                                              2600                                                                             1560                                                                             16  28  12  "                                 32-14                                                                             207                                                                              115,000                                                                             2.12 "    688                                                                              2575                                                                             1775                                                                             18  22  9   "                                 32-15                                                                             "  "     "    "    689                                                                              2575                                                                             1840                                                                             20  23  --  "                                 32-16                                                                             "  "     "    "    688                                                                              2560                                                                             1850                                                                             20  21  --  "                                 32-17                                                                             "  "     "    "    689                                                                              2575                                                                             1910                                                                             25  21  --  "                                 32-18                                                                             213                                                                              "     2.06 "    690                                                                              2600                                                                             2125                                                                             19  22  --  "                                 32-20                                                                             205                                                                              111,000                                                                             "    72.7 689                                                                              2590                                                                             2100                                                                             16  20  --  "                                 32-21                                                                             "  "     "    "    690                                                                              2570                                                                             1900                                                                             16  19  --  "                                 32-23                                                                             "  "     "    "    "  2560                                                                             1810                                                                             20  15  --  "                                 32-24                                                                             "  "     "    "    "  "  1890                                                                             21  15  --  "                                 32-25                                                                             "  "     "    "    "  "  1950                                                                             19  20  1   "                                 32-26                                                                             "  "     "    "    691                                                                              2580                                                                             2100                                                                             21  20  1   "                                 32-27                                                                             "  "     "    "    "  "  2100                                                                             22  18  2   "                                 32-28                                                                             "  "     "    "    "  "  2110                                                                             23  18  2   "                                 32-29                                                                             "  "     "    "    "  2575                                                                             1200                                                                             21  16  2   "                                 32-30                                                                             "  "     "    "    "  2575                                                                             1690                                                                             20  16  2   "                                 32-31                                                                             "  "     "    "    690                                                                              2580                                                                             1750                                                                             20  14  2   "                                 32-32                                                                             "  "     "    "    690                                                                              "  1740                                                                             20  14  1   "                                 32-33                                                                             "  "     "    "    691                                                                              "  1710                                                                             21  14  1   "                                 32-34                                                                             "  "     "    "    "  "  1740                                                                             20  14  1   "                                 32-35                                                                             "  "     "    "    "  "  1810                                                                             21  14  0   "                                 32-36                                                                             "  "     "    "    690                                                                              2525                                                                             1640                                                                             20  13  0   "                                 32-41                                                                             245                                                                              123,000                                                                             1.93 81.5 778                                                                              2575                                                                             2560                                                                              4   3  1   Minimum preheat, lean             32-42                                                                             242                                                                              123,000                                                                             1.96 "    761                                                                              2560                                                                             2550                                                                              5   3  0   "                                 32-43                                                                             235                                                                              124,000                                                                             2.01 "    745                                                                              2580                                                                             2560                                                                              5   3  0   "                                 32-45                                                                             235                                                                              "     2.01 "    725                                                                              2550                                                                             2525                                                                              5   3  0   "                                 32-47                                                                             218                                                                              "     2.17 "    698                                                                              2575                                                                             2550                                                                              5   4  0   "                                 32-48                                                                             205                                                                              "     2.31 "    675                                                                              2600                                                                             2580                                                                              5   5  3   "                                 32-49                                                                             205                                                                              "     2.31 "    646                                                                              2580                                                                             2560                                                                              5   4  2   "                                 32-50                                                                             201                                                                              125,000                                                                             2.36 "    623                                                                              2590                                                                             2570                                                                              5   5  2   "                                 32-51                                                                             196                                                                              125,000                                                                             2.41 "    599                                                                              2575                                                                             2550                                                                              5   4  3   "                                 32-52                                                                             193                                                                              123,000                                                                             2.41 80.1 574                                                                              2570                                                                             2550                                                                              5   4  2   "                                 32-54                                                                             190                                                                              126,000                                                                             2.52 82.5 582                                                                              2600                                                                             2590                                                                              5   5  1   "                                 32-56                                                                             188                                                                              143,000                                                                             2.87 93.2 550                                                                              2600                                                                             2590                                                                              5   5  2   "                                 32-57                                                                             160                                                                              126,000                                                                             2.95 81.5 500                                                                              2575                                                                             2550                                                                              6   4  0   "                                 32-58                                                                             176                                                                              137,000                                                                             "    89.3 440                                                                              2560                                                                             "   6   4  0   "                                 32-59                                                                             176                                                                              137,000                                                                             "    89.3 400                                                                              2570                                                                             "   6   4  0   "                                 32-61                                                                             179                                                                              121,000                                                                             2.55 78.6  750*                                                                            2500                                                                             2490                                                                              6   4  0   "                                 32-62                                                                             173                                                                              107,000                                                                             2.33 69.4  762*                                                                            2500                                                                             2490                                                                              6   4  0   "                                 32-65                                                                             210                                                                              154,000                                                                             2.79 101  645                                                                              2600                                                                             2575                                                                              5   4  0   Maximum throughput                32-66                                                                             217                                                                              219,000                                                                             3.82 144  649                                                                              "  --  6   4  0   "                                 32-67                                                                             216                                                                              229,000                                                                             4.05 150  656                                                                              "  --  6   4  0   "                                 32-68                                                                             218                                                                              232,000                                                                             4.05 152  646                                                                              "  2560                                                                              6   4  0   "                                 __________________________________________________________________________

What is claimed is:
 1. A catalytically active structurally sound ceramicin a monolithic form having gas flow passages with heterogeneouscombustion surfaces formed of a catalytically active mixed base metaloxide of the perovskite, spinel, corundum or ilmenite crystal structurefor the sustained combustion of fuels.
 2. A monolithic catalyticstructure comprising a catalytically active mixed base metal oxide ofthe perovskite crystal structure ABO₃ in intimate admixture with anadditional base metal oxide of the perovskite crystal structure ABO₃suitable for forming structurally sound catalytic ceramics.
 3. Acatalytic structure as in claim 2 in which the active metal oxide iscomprised of a metal of the cation B selected from the group consistingof Cr, Ni, Mn, Fe, Sr, and Ca.
 4. A catalytic structure as in claim 2 inwhich the additional metal oxide is comprised of a metal of the cation Aselected from the group consisting of La and Sr and is further comprisedof a metal of the cation B selected from the group consisting of Al andCr.
 5. A monolithic catalytic structure comprising a catalyticallyactive base metal oxide of the spinel crystal structure A[B₂ ]O₄ orB[AB]O₄ in intimate admixture with an additional base metal oxide of thespinel crystal structure suitable for forming structurally soundcatalytic ceramics.
 6. A catalytic structure as in claim 5 in which theactive metal oxide is comprised of a metal of the cation B selected fromthe group consisting of Ni, Fe and Cr.
 7. A catalytic structure as inclaim 5 in which the active metal oxide comprises Fe₃ O₄ or NiAl₂ O₄ andthe additional metal oxide comprises MgAl₂ O₄.
 8. A catalytic structureas in claim 5 in which the active metal oxide comprises Fe₃ O₄ with Cr.9. A monolithic catalytic structure comprising a catalytically activebase metal oxide of the corundum crystal structure B₂ O₃ or of theilmenite crystal structure ABO₃ in intimate admixture with an additionalbase metal oxide of the corundum crystal structure suitable forformation of a structurally sound catalytic ceramic.
 10. A catalyticstructure as in claim 9 in which the active metal oxide of the corundumstructure is comprised of a metal of the cation B selected from thegroup consisting of Co and Fe.
 11. A catalytic structure as in claim 9in which the active metal oxide of the ilmenite structure is comprisedof a metal selected from the group consisting of Fe and Cr.
 12. Acatalytic structure as in claim 10 or 11 in which the additional metaloxide is comprised of the metal Al of the cation B.
 13. A catalyticstructure as in claim 9 in which the active metal oxide comprisesyttria-stabilized Co₂ O₃ of corundum crystal structure.
 14. A combustionprocess comprising combusting reactants in the presence of acatalytically active structurally sound ceramic in a monolithic formhaving gas flow passages with heterogeneous combustion surfaces formedof a catalytically active base metal oxide of the perovskite, spinel,corundum or ilmenite crystal structure for the sustained combustion offuels.
 15. A combustion process comprising combusting reactants in thepresence of a catalytically active structurally sound ceramic in amonolithic form having gas flow passages with heterogeneous combustionservices formed of a catalytically active base metal oxide of theperovskite crystal structure ABO₃ in intimate admixture with additionalbase metal oxide of the perovskite crystal structure ABO₃ suitable forforming structurally sound catalytic ceramics.
 16. A combustion processas in claim 15 in which the active metal oxide is comprised of a metalof the cation B selected from the group consisting of Cr, Ni, Mn, Fe,Sr, and Ca.
 17. A combustion process as in claim 15 in which theadditional metal oxide is comprised of a metal of the cation A selectedfrom the group consisting of La and Sr and is further comprised of ametal of the cation B selected from the group consisting of Al and Cr.18. A combustion process comprising combusting reactants in the presenceof a monolithic catalytic structure comprising a catalytically activebase metal oxide of the spinel crystal structure A[B₂ ]O₄ or B[AB]O₄ inintimate admixture with an additional base metal oxide of the spinelcrystal structure suitable for forming structurally sound catalyticceramics.
 19. A combustion process as in claim 18 in which the activemetal oxide is comprised of a metal of the cation B selected from thegroup consisting of Ni, Fe and Cr.
 20. A combustion process as in claim18 in which the active metal oxide comprises Fe₃ O₄ or NiAl₂ O₄ and theadditional metal oxide comprises MgAl₂ O₄.
 21. A combustion process asin claim 18 in which the active metal oxide comprises Fe₃ O₄ with Cr.22. A combustion process comprising combusting reactants in the presenceof a monolithic catalytic structure comprising a catalytically activebase metal oxide of the corundum crystal structure B₂ O₃ or of theilmenite crystal structure ABO₃ in intimate admixture with an additionalbase metal oxide of the corundum crystal structure suitable forformation of a structurally sound catalytic ceramic.
 23. A combustionprocess as in claim 22 in which the active metal oxide of the corundumstructure is comprised of a metal of the cation B selected from thegroup consisting of Co and Fe.
 24. A combustion process as in claim 22in which the active metal oxide of the ilmenite structure is comprisedof a metal selected from the group consisting of Fe and Cr.
 25. Acombustion process as in claim 23 or 24 in which the additional metaloxide is comprised of the metal Al of the cation B.
 26. A combustionprocess as in claim 22 in which the active metal oxide comprisesyttria-stabilized Co₂ O₃.
 27. A method of formulating a catalyst systemcomprising the steps of preparing an intimate admixture of acatalytically active base metal oxide having the perovskite crystalstructure and an average particle size on the order of 10-20 micronswith an additional base metal oxide having the perovskite crystalstructure of the type suitable for formation of structurally soundcatalytic ceramics and with an average particle size on the order of10-20 microns, forming the mixture into a unitary structure, andcalcining the formed structure.
 28. A method of formulating a catalystsystem comprising the steps of preparing an intimate admixture of acatalytically active base metal oxide of the spinel crystal structureand an average particle size on the order of 10-20 microns with anadditional base metal oxide of the spinel crystal structure of the typesuitable for formation of structurally sound catalytic ceramics and withan average particle size on the order of 10-20 microns, forming themixture into a unitary structure, and calcining the formed structure.29. A method of formulating a catalyst structure comprising the steps ofpreparing an intimate admixture of a catalytically active base metaloxide of the corundum crystal structure or of the ilmenite crystalstructure, said active metal oxides having an average particle size onthe order of 10-20 microns, with an additional base metal oxide of thecorundum crystal structure of the type suitable for formation ofstructurally sound catalytic ceramics and having an average particlesize on the order of 10-20 microns, forming the mixture into a unitarystructure, and calcining the formed structure.